/*******************************************************************************
 * Copyright (c) 2004 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/

package org.eclipse.birt.chart.datafeed;

/**
 * This interface maintains a subset of a resultset by defining a selective list
 * of columns and a row range to be extracted from a full resultset. An
 * implementor of this is provided to a custom data set processor that is
 * capable of converting the resultset subset content into the expected chart
 * dataset format.
 */
public interface IResultSetDataSet
{

	/**
	 * @return Returns the columns count for current resultset subset.
	 */
	int getColumnCount( );

	/**
	 * Returns the data type associated with a single column resultset subset.
	 * Note the result is only valid for single column subset.
	 * 
	 * @return A data type associated with a single column resultset
	 */
	int getDataType( );
	
	/**
	 * Returns the data type of a given column associated with a multi-column resultset subset.
	 * 
	 * @return A data type associated with a multi-column resultset
	 */
	int getDataType( int columnIndex );
	
	/**
	 * Returns the number of rows associated with this resultset subset instance
	 * 
	 * @return The number of rows associated with this resultset subset instance
	 */
	long getSize( );

	/**
	 * Indicates whether another row of data is available without actually
	 * moving the cursor
	 * 
	 * @return 'true' if another row of data is available
	 */
	boolean hasNext( );

	/**
	 * Returns a row of data and advances the resultset subset cursor
	 * 
	 * @return An 'Object[]' that represents a resultset subset tuple
	 */
	Object[] next( );
}
